Process for the production of organic solutions of percarboxylic acids

ABSTRACT

Water free solutions of percarboxylic acids having two to four carbon atoms are prepared by extracting aqueous solutions of the percarboxylic acids with phosphate esters having three to 30 carbon atoms, desorbing the extract with a solvent and dehydrating the solvent, in a given case by azeotropic distillation, if necessary after addition of a carboxylic acid ester boiling below the percarboxylic acid.

United States Patent [191 Schreyer et al.

[ 1 PROCESS FOR THE PRODUCTION OF ORGANIC SOLUTIONS OF PERCARBOXYLIC ACIDS [75] Inventors: Gerd Schreyer, Grossauheim; Otto 'Weiberg, Neu-Isenburg, both of Germany v [73] Assignee: Deutsche Gold-und Silber-Scheidean-stalt Vormals Roessler, Frankfurt am Main, Germany [22] Filed: July 25, 1972 [21] Appl. No.: 274,965

[30] Foreign Application Priority Data Sept. 13, 1971 Germany 2145604 [52] U.S. C1 252/186, 8/111, 252/95, 252/99, 252/104, 260/502 R, 260/610 A [51] Int. Cl ..C1ld 7/56 [58] Field of Search 252/186, 95, 99, 104; 8/111; 260/502 R, 610 A Oct. 1, 1974 [56] References Cited UNITED STATES PATENTS 3,169,986 2/1965 Webb 260/502 R FOREIGN PATENTS OR APPLlCATIONS 731,188 3/1966 Canada 260/502 R Primary ExaminerCarl D. Quarforth Assistant Examiner lrwin Gluck Attorney, Agent, or Firm-Cushman, Darby & Cushman [5 7] ABSTRACT 16 Claims, N0 Drawings 1 PROCESS FOR THE PRODUCTION OF ORGANIC SOLUTIONS OF PERCARBOXYLIC ACIDS The present invention is concerned with a process for the production of water free solutions of percarboxylic acids having two to four carbon atoms.

The production of water free solutions of percarboxylic acids, especially peracetic acid is known and is described in the following articles:

Ullmann, Encycl. d. techn. Chemie Erg. Vol., 1970, Neve Verfahren, pages 181 et seq., Urban and Schwarzenberg, Munich;

Kirk-Othmer, Encyclopedia of Chemical Technology, first edition, first Supplement Volume, pages 622 et seq., lnterscience, New York, 1957;

Swern, Organic Peroxides, Vol. I, page 313 et seq., Wiley-Interscience, New York, 1970.

The production of organic percarboxylic acid solutions by known processes is uneconomical in industrial operation because in order to guarantee safety an unusually high expenditure is necessary for regulating and safety devices. In the production of percarboxylic acids from hydrogen peroxide and carboxylic acids in the presence of organo'solvents and water therefore care must be taken that once the reaction has completely terminated, namely by removal of the water, on the. other hand there is not allowed to occur a concentration of the percarboxylic acid in organic solvents which cause explosive mixtures to form. Therefore in the processing of peroxy compounds the process conditions are adhered to very exactly because slight deviations lead to the formation of mixtures capable of explosion. Water free solutions are formed to be sure directly by oxidation of aldehydes which process can be carried out in either the liquid or the gas phase. However, in this process there are formed on the one hand extraordinarily dangerous intermediate products and on the other hand there accumulates after the reactionof the percarboxylic acid the corresponding carboxylic acids as byproducts which is exceedingly undesirable.

- In the known methods of production the organic solutions stand for a long time, in part at elevated temperature, and under drastic chemical conditions which are provided by the presence of acid catalysts with hydrogen peroxide and percarboxylic acids in contact whereby the breakdown of the solvent with formation of disturbing byproducts is favored.

The present process was developed to avoid these disadvantages. In the present process organic solvents are added for the first time after the end of the formation of the percarboxylic acid, wherein, in comparison to the known processes, a simple and safe reaction procedure as well as a reduction in decomposition of the organic solvent is achieved.

It has now been found that organic percarboxylic acid solutions can be produced safely if aqueous solutions of percarboxylic acids having two to four carbon atoms, specifically the peralkanoic acids, 'peracetic acids, perpropionic acid, perisobutyric acid and perbutyric acid, are extracted with organic phosphates having three to 30 carbon atoms whereupon the extract is desorbed with an organic solvent, preferably an ester of a carboxylic acid having four to carbon atoms, e.g., an alkyl alkanoate, and the desorbate of percarboxylic acid and solvent dehydrated, in a given case by azeotropic distillation, if necessary after addition of a carboxylic acid ester boiling below the percarboxylic acid.

-In this manner there are obtained the desired organic solutions of percarboxylic acids in a simple and economical manner.

As aqueous solutions of percarboxylic acids there are preferably employed those prepared by German Pat. Nos. 1,165,576 and 1,170,926. The entire disclosure of these two German patents is hereby incorporated by reference. The concentration of the aqueous percarboxylic acid can be between 10 and percent, preferably 20 to 60 percent.

Unless otherwise indicated all parts and percentages are by weight.

As phosphate esters there can be employed tertiary phosphates of the formula where R R and R are the same or different and are alkyl, aryl or aralkyl and have a total of three to 30 carbon atoms.

Examples of suitable extraction agents are trimethyl phosphate, tributyl phosphate, trioctyl phosphates, dioctylphenyl phosphate, triethyl phosphate, tripropyl phosphate, triisobutyl phosphate, triamyl phosphate,

formate, methyl propionate, ethyl propionate, methyl I butyrate, ethyl butyrate, methyl valerate, sec-hexyl acetate, propyl propionate, butyl propionate, amyl propionate, methyl isobutyrate, ethyl valerate, propyl isovalerate, methyl caproate, methyl pivalate, ethyl pivalate, propyl pivalate, isopropyl pivalate, butyl pivalate, secbutyl pivalate and amyl pivalate. Other desorbants are mentioned later in the specification.

The esters employed to aid in the dehydration can be the same as those set forth above so long as they boil below the percarboxylic acid.

The extraction is preferably carried out continuously, best by countercurrent operation, namely in conventional extraction apparatus such as for example extraction columns with plates or packing with or without pulsation. As packing there can suitably be added rings, saddles or helices. As plates there can be used perforated plates, tunnel plates or bubble trays.

The aqueous percarboxylic acid is fed below the top of the column and the phosphate ester at the lower end of the column. A largely water free solution of percarboxylic acid is drawn off at the top of the column while the raffinate which contains negligibly small amounts of active oxygen is withdrawn from the lower end. The amount of ester used is determined by special solvent loading curve and by the required coucentration of percarboxylic acid.

To desorb the percarboxylic acid the extract is fed to a thin film evaporator, preferably with moving inner zene, toluene, xylene, and ethyl benzene or mixtures of such solvents. Preferably there are used, however, carboxylic acid esters containing four to 10 carbon atoms or mixtures containing them.

parts, operating in a vacuum. Simultaneously the nec- 5 Th concentration of the organic solvent percarboxessary amount of solvent is supplied to the evaporator, ylic acid solution on the lower side is determined by mwherein a portion of the solvent is fed to the lower end dustrial considerations and on the upper side by the of the evaporator in vapor form. The amount of solvent danger motive. The solutions therefore can contain a is determined likewise by the required concentration of concentration of to 60 percent, preferably to 50 percarboxylic acid. 10 percent of the percarboxylic acid.

By condensation of the desorbate water containing The extraction can be operated at normal pressure at percarboxylic acid solutions in organic solvents are obtemperatures of 5 to 50C., preferably at 10 to C. tained. For many purposes the water content of the so- The azeotropic dehydration and desorption are carried lution, e.g., does not play a disturbing role so that the Out n a Vacuum a! 20 I0 400 TOIT, p a y 5010 250 organic percarboxylic acid solution is usable directly 15 To he sump temperature is to 100C, preferawithout a previous azeotropic distillation. bly to C.

if water free organic percarboxylic acids are required The invention is further eXPlaihed y the following the desorbate is preferably fed to a continuously operexamples. W ating distillation plant which is provided at the top with V EXAMPLES a separator for the water taken off while the percarbox- 20 A Apparatus Employed: The extraction unit wit the y acid Solution is drawn f l he 59mg necessary equipment consisted of a tube 2 meters long If a carboxylic acid ester having ahigher boiling point d having a diameter of 2.8 cm in which the e Were than the percarboxylic acid is used for the desorption located 40 screens having a hole diamete o 1 then there must be added to the desorbate a carboxylic: The column was pulsated with a pulsation pump and acid ester having a lower boiling point than the percar- 25 operated in countercurrent manner. The results of the boxylic acid. The carboxylic acid ester is so selected extraction experiments are Set forth in te following exthat only slight amounts of the percarboxylic acid distill amples. W M ,A e -E d H N Vol Ratio PES Content Water vs.

S5597z PES Content Amount Extraction I Extraction rganic ater Organic Added in Example Agent Agent Phase Phase Phase g/l the Extract 1 tributyl phosphate l:2.72 178 1.7 45.4 99.9

2 tributyl phosphate 121.36 291 9.2 55.4 99.2

3 triocytyl phosphate 1:3 .07 167 64.5 13.1 97.3

4 triocytyl phosphate 1:5.93 98 4.0 12.0 99.8

PES pcracetic acid.

off from the desorbate together with the water and entraining agent. Thereby there is safely prevented the build up of dangerously high percarboxylic acid concentrations in the column and the boiling point of the mixture is reduced. The amount of lower boiling ester can be determined by one skilled in the art by a simple preliminary test.

For the desorption there can be used all organic solvents which are lower boiling than the phosphate esters, for example carboxylic acid esters such as those set forth above, chlorinated hydrocarbons, e.g., carbon tetrachloride, chloroform, ethylene dichloride, acety- The other peracids, e.g., perpropionic acid and perisobutyric acid can be extracted with equally good success. The yield of active oxygen and the purity of the product in such cases corresponds to that with peracetic acid.

B. Desorption Apparatus: For desorption the extract from the extraction unit described above was fed into thin film evaporator having internal moving parts and operating in a vacuum. Simultaneously with the extract there were fed to the evaporator a solvent for desorption, partially in liquid form and partially in vapor form at the lower end of the thin layer evaporator.

lene tetrachloride, ethylene trichloride, 1,2-- Examples BI"B3 in the fOIlOWihg table Show the dichlQroethylene, r at c, oq rbqns .s-a. Pen: 5"! 9f *1? @Sfil'lll. teseu aci Volume PES Content Water Content PES Ratio 31/1 in all PES vs. Example Extracted Added Extract Extract Product Extract Product added in the B In Solvent Solvent Added dded Distillation 1 tributyl n-butyl phosphate acetate 1.05:1 291 230 55.4 42.4 96.0

2 trioctyl n-butyl phosphate acetate 2.17:1 164 263 12.4 19.4 96.2

3 trioctyl ethyl not phosphate acetate 2.17:1 164 284 12.4 observed 98.7

PES peracetic acid General Conditions:

ressure 50 Torr vaporator temperature =100C.

Just as in the extraction good results are obtaiiie d where perpropionic acid or perisobutyric acid is employed in the desorption. The desorbate obtained can Conditions for the Dehydration:

Example C Pressure: 250 Torr; Head Temperature: about 42C.

Sump temperature: 5560C.

At 30% peracetic acid in ethyl acetate.

What is claimed is:

l. A process forv the production of water free solutions of percarboxylic acids having two to four carbon atoms comprising extracting the aqueous solution of the percarboxylic acid with a tertiary phosphate ester having three to carbon atoms and desorbing the extract with a solvent for said percarboxylic acid selected from the group consisting of hydrocarbyl alkanoates having four to 10 carbon atoms, chlorinated aliphatic hydrocarbons and aromatic hydrocarbons, said solvent boiling lower than said phosphate ester.

2. A process according to claim 1 wherein the percarboxylic acid is a peralkanoic acid and the phosphate h ths .iqr l .W WWW.

where R R and R are alkyl, aryl or aralkyl.

3. A process according to claim 2 including the additional step of removing the final amount of water from the desorbate by azeotropic distillation with a hydro- 4. A process according to claim 3 wherein the de- 4 5. A process according to claim 3 wherein the desorbing solvent boils below the percarboxylic acid.

6. A process according to claim 2 wherein the percarboxylic acid is peracetic acid.

7. A process according to claim 2 wherein the aqueous percarboxylic acid solution contains 10 to percent of percarboxylic acid.

8. A process according to claim 7 wherein the phosphate ester is trimethyl phosphate, tributyl phosphate or trioctyl phosphate.

9. A process according to claim 7 wherein the desorption is carried out with a hydrocarbyl alkanoate having four to 10 carbon atoms.

10. A process according to claim 9 wherein the hydrocarbyl alkanoate is an alkyl alkanoate.

11. A process according to claim 9 wherein the hydrocarbyl alkanoate is an alkyl alkanoate or cyclohexyl alkanoate.

20 12. A process according to claim 2 including the ad- 14. A process according .to claim 13 wherein the alkyl acetate is n-butyl acetate.

15. A process according to claim 13 wherein the alkyl acetate is ethyl acetate.

16. A process according to claim 2, wherein the solvent is selected from the group consisting of ethyl acetate, propyl acetate, butyl acetate, amyl acetate, 2- ethyl-hexyl acetate, cyclohexyl acetate, t-butyl acetate, isoamyl acetate, propyl formate, butyl formate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate, methyl valerate, sec. hexyl acetate, propyl propionate, butyl propionate, amyl propionate, methyl isobutyrate, ethyl valerate, propyl isovalerate, methyl caproate, methyl pivalate, ethyl pivalate, propyl pivalate, isopropyl pivalate, butyl pivalate, see-butyl pivalate, amyl pivalate, carbon tetrachloride, chloroform, ethylene dichloride, acetylene tetrachloride, ethylene trichloride, l,2-dichloroethylene, benzene, toluene, xylene and ethyl benzene. 

1. A PROCESS FOR THE PRODUCTION OF WATER FREE SOLUTIONS OF PERCARBOXYLIC ACIDS HAVING TWO TO FOUR CARBON ATOMS COMPRISING EXTRACTING THE AQUEOUS SOLUTION OF THE PERCARBOXYLIC ACID WITH A TERTIARY PHOSPHATE ESTER HAVING THREE TO 30 CARBON ATOMS AND DESORBING THE EXTRACT WITH A SOLVENT FOR SAID PERCARBOXYLIC ACID SELECTED FROM THE GROUP CONSISTING OF HYDROCARBYL ALKANOATES HAVING FOUR TO 10 CARBON ATOMS, CHLORINATED ALIPHATIC HYDROCARBONS AND AROMATIC HYDROCARBONS, SAID SOLVENT BOILING LOWER THAN SAID PHOSPHATE ESTER.
 2. A process according to claim 1 wherein the percarboxylic acid is a peralkanoic acid and the phosphate has the formula
 3. A process according to claim 2 including the additional step of removing the final amount of water from the desorbate by azeotropic distillation with a hydrocarbyl alkanoate having four to 10 carbon atoms boiling below the percarboxylic acid.
 4. A process according to claim 3 wherein the desorbing solvent boils above the percarboxylic acid.
 5. A process according to claim 3 wherein the desorbing solvent boils below the percarboxylic acid.
 6. A process according to claim 2 wherein the percarboxylic acid is peracetic acid.
 7. A process according to claim 2 wherein the aqueous percarboxylic acid solution contains 10 to 80 percent of percarboxylic acid.
 8. A process according to claim 7 wherein the phosphate ester is trimethyl phosphate, tributyl phosphate or trioctyl phosphate.
 9. A process according to claim 7 wherein the desorption is carried out with a hydrocarbyl alkanoate having four to 10 cArbon atoms.
 10. A process according to claim 9 wherein the hydrocarbyl alkanoate is an alkyl alkanoate.
 11. A process according to claim 9 wherein the hydrocarbyl alkanoate is an alkyl alkanoate or cyclohexyl alkanoate.
 12. A process according to claim 2 including the additional step of removing the final amount of water from the desorbate by azeotropic distillation with an alkyl alkanoate having four to 10 carbon atoms boiling below the percarboxylic acid.
 13. A process according to clai 2 wherein the solvent is an alkyl acetate having four to 10 carbon atoms.
 14. A process according to claim 13 wherein the alkyl acetate is n-butyl acetate.
 15. A process according to claim 13 wherein the alkyl acetate is ethyl acetate.
 16. A process according to claim 2, wherein the solvent is selected from the group consisting of ethyl acetate, propyl acetate, butyl acetate, amyl acetate, 2-ethyl-hexyl acetate, cyclohexyl acetate, t-butyl acetate, isoamyl acetate, propyl formate, butyl formate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate, methyl valerate, sec. hexyl acetate, propyl propionate, butyl propionate, amyl propionate, methyl isobutyrate, ethyl valerate, propyl isovalerate, methyl caproate, methyl pivalate, ethyl pivalate, propyl pivalate, isopropyl pivalate, butyl pivalate, sec.-butyl pivalate, amyl pivalate, carbon tetrachloride, chloroform, ethylene dichloride, acetylene tetrachloride, ethylene trichloride, 1,2-dichloroethylene, benzene, toluene, xylene and ethyl benzene. 